docs: def expectScreen(self, filename, maxrms=0):
          """ Wait until the display matches a target image
  
              filename: an image file to read and compare against
              maxrms: the maximum root mean square between histograms of the
                      screen and target image
          """
          log.debug('expectScreen %s', filename)
          return self._expectFramebuffer(filename, 0, 0, maxrms)